Cardiac arrhythmia is a condition in which the heart's normal rhythm is disrupted. There are many types of cardiac arrhythmias, including supraventricular arrhythmias that begin above the ventricles (such as premature atrial contractions (PACs), paroxysmal supraventricular tachycardia (PSVT), accessory pathway tachycardias, atrial fibrillation, and AV nodal reentrant tachycardia (AVNRT), ventricular arrhythmias that begin in the lower chambers of the heart (such as premature ventricular contractions (PVCs), ventricular tachycardia (VT), ventricular fibrillation, and long QT syndrome), and bradyarrhythmias that involve slow heart rhythms and may arise from disease in the heart's conduction system.
Atrial fibrillation (AF) is the most common cardiac arrhythmia, in which disorganized electrical impulses (usually generated by the roots of the pulmonary veins) interrupt the normal electrical impulses generated by the sinoatrial node, which in turn causes an irregular conduction of electrical impulses to the heartbeat-generating ventricles. AF may result from a number of conditions, such as hypertension, coronary artery disease, pericarditis, lunch disease, hyperthyroidism, carbon monoxide poisoning, or rheumatoid arthritis. Indeed, AF itself may increase the likelihood of stroke by as much as sevenfold.
Catheter ablation is frequently used to treat AF, and involves a minimally invasive procedure by which areas of cardiac tissue that facilitate the irregular electrical conduction are ablated using any of a number of energy modalities. For example, one or more pulmonary veins (PVs) may be targeted. AF is commonly initiated by foci located in the PVs, which are large blood vessels that carry oxygenated blood from the lungs to the left atrium (LA) of the heart. In order to disrupt the propagation of abnormal electrical currents, the ablation catheter may be placed around the opening of the PV to the heart and/or within the PV where the foci are located. However, the PVs are usually not regularly shaped, and often have an asymmetrical interior that can be difficult to navigate. Further, it can be very difficult to navigate a catheter through the septum and into the PVs, particularly the right inferior PV. Balloon catheters may be used to ablate within or on the ostium of a PV, but it is often difficult to properly seat the balloon within the vein or at the ostium to ensure proper tissue contact and/or occlusion of the vein.
Accordingly, it is desired to provide a catheter that is more easily navigated within a patient's vasculature and can be more accurately positioned for performing certain medical procedures, such as pulmonary vein isolation in the treatment of cardiac arrhythmia, such as atrial fibrillation, while reducing the risk of patient injury.